1. Field of the Invention
The present invention relates to a fixing instrument for a spinal fusion member that is used to secure spinal fusion members together, which are attached to both sides of a spine to correct a distortion of the spine.
2. Description of the Related Art
As one treatment for patients who suffer from spondylolisthesis, abnormal curvature of the spine and the like, corpus vertebrae which constitute a distorted spine are coupled together vertically by an elongated spinal fusion member and the distortion is corrected by the rigidity of the spinal fusion member.
In this case, a surgeon dissects the back of a patient to expose the vertebrae. Then, the spinal fusion members are fixed on the both sides of each of the vertebrae with screws secured to lengthwisely apart portions of the spinal fusion members.
Further, to correct the distortion of the spine in the twisting direction, a screw structure is laid out with the axis of the screw perpendicular to both spinal fusion members to apply them force in the direction approaching each other.
According to this method, however, only the peripheral surface of the screw Structure faces the dissected portion of a patient. Fastening the screw therefore requires gradual turning of a wrench in a narrow space formed in the patient's body by dissection, thus making the surgical operation troublesome.